Implementing a Tiered Genetic Testing Strategy for Muscular Dystrophies in Morocco: From Targeted Assays to Exome Sequencing

INTRODUCTION: Muscular dystrophies (MDs) are a heterogeneous group of inherited neuromuscular disorders. In Morocco, where consanguinity is common, recurrent variants have been reported; however, the overall molecular landscape remains underexplored. METHODS: We analyzed 716 patients referred over 32 years for suspected limb-girdle muscular dystrophy (LGMD) or dystrophinopathy using a stepwise approach. Multiplex PCR (MPCR) for DMD deletions and targeted Sanger sequencing of the SGCG:c.525delT variant were performed as first-line tests. Unsolved patients underwent next-generation sequencing (NGS), either via a customized gene panel or whole-exome sequencing (WES). RESULTS: Multiplex PCR for DMD deletions and targeted Sanger sequencing of the SGCG:c.525delT variant resolved nearly half of cases, demonstrating the efficiency of these cost-effective first-line tests. Unsolved patients underwent next-generation sequencing (NGS), via a customized gene panel or whole-exome sequencing (WES), though resource limitations prevented full coverage. Among tested cases, SGCA, CAPN3, and FKRP were the most frequently mutated genes after DMD and SGCG, with several novel or recurrent variants suggesting population-specific alleles. CONCLUSIONS: These results highlight the genetic heterogeneity of MDs in Morocco and the value of combining targeted and broad genomic approaches, while underscoring the need to extend NGS to fully characterize unresolved patients.